Dear Sir,

I thank you cordially for your singularly kind letter.² But your kindness leads me to overrate what I have done in Natural history.— I was much surprised at the appearance of the leaf of the hybrid strawberry;³ and was much tempted to accept your kind offer and declined only on reflection, that as my health is weak and I have many other points to attend to, I feared I should have neglected your specimen. Perhaps you will be so good as to inform me whether this hybrid produces next spring fertile seeds. If I understand right the supposed progeny from the strawberry and raspberry have not yet fruited: but if this be really a cross you will indeed have effected a prodigy, and it will be very curious if you cross Blackberry and Raspberry;⁴ I shall much like to hear the result. I may mention that this past spring I tried again the crosses on Primula with the same result rather more strongly marked; and I have gone on, now for three generations breeding them what I call homomorphically, with some curious results, which I shall publish whenever I have time.⁵ I have sent a paper on Linum to the Linnæan Society;⁶ when it is published I will do myself the pleasure of sending to you a copy; and it will I should think be in good time for your experiments.⁷ I cannot say how glad I am that you will make some experiments on the subject.

It does not absolutely follow in making a cross between distinct species, that the same rules would follow in the fertility of the pollen. I hope that you will try and mark separately (excluding insects, as you know better than I do, the necessity) the two kinds of pollen of one species on the stigma of the other; and see in making hybrids what the difference is in fertility, and in the character of the hybrid seedlings. This would be an entirely new field for observation and discovery. You will see in my paper that some species of Linum are not dimorphic, and are self-fertile; and so it is in some other genera.—⁸ You refer to L. rubrum; I am not a Botanist and have called one of the species on which I have experimented L. grandiflorum, which is crimson and not uncommon in flower gardens; I hope I have not made a mistake in name.—⁹

You most kindly permit me to mention any point on which I want information. If you are so inclined, I am curious to know from systematic experiments, whether M^r. D. Beaton’s statement that the pollen of two shortest anthers of scarlet Pelargonium produce dwarf plants, in comparison with plants produced from same mother-plants by the pollen of longer stamens from same flower.¹⁰ It would aid me much in some laborious experiments on Melastomas.¹¹ I confess I feel a little doubtful: at least I feel pretty nearly sure that I know the meaning of short stamens in most plants. This summer (for another object) I crossed Queen of Scarlet Pelargonium with pollen of long and short stamens of Multiflora alba, and it so turns out that plants from short-stamens are the tallest; but I believe this to have been mere chance.—¹² My few crosses in Pelargonium were made to get seed from the central peloric or regular flower (I have got one from peloric flower by pollen of peloric); and this leads me to suggest that it would be very interesting to test fertility of peloric flowers in three ways, own peloric pollen on peloric stigma—common pollen on peloric stigma—peloric pollen on common stigma of same species. My object is to discover whether with change of structure of flower there is any change in fertility of pollen or of female organs. This might, also, be tested by trying peloric and common pollen on stigma of a distinct species, and conversely.¹³ I believe there is a peloric and common variety of Tropæolum; and a peloric or upright and common variation of some species of Gloxinia.—¹⁴ And the medial peloric flowers of Pelargonium; and probably others unknown to me.—

To recur to Linum; if you cross distinct species, it would, I think be advisable to take two dimorphic species; and not one dimorphic and the other self-fertile. I have reason to suspect L. trigynum is dimorphic but it has not yet flowered with me.—¹⁵

Your kindness has led me to trespass at unreasonable length on your time, and, | I remain dear Sir, | yours truly obliged. | Ch. Darwin.

P.S. I thank you for your most kind invitation, which I fear I shall never profit by.—¹⁶

P.S. Have you any quite sterile Hybrid plant with a rather large stigma, (and of which I could procure either one or both pure parent flowers) as I very much wish to compare by dissection certain minute parts of stigma: if so, and you would have great kindness to send me by Post in a little tin box some flowers, it would be a very great favour.¹⁷